The present invention relates to a detachable combination shoe-pedal assembly for use in cycling. More particularly, the invention relates to a pedal assembly that permits a cycling shoe-pedal assembly to operably engage and safely disengage the pedal crank arm of a bicycle or other pedal powered apparatus.
Many modern bicycles, including those intended for road racing, are designed to transfer and convert the linear forces applied by the cyclist into rotational motion of the crank arm and sprocket. In conventional bicycles, the forces generated by the cyclist are exerted through the pedal assembly in the vertical direction when the pedal is depressed by the rider""s foot as well as lifted on the upstroke. A popular configurations for road racing is the clipless pedal system comprising a pedal with a receptacle adapted to receive a cleat mounted in the sole of a special cycling shoes. This cleat snaps into the pedal receptacle allowing the cyclist to connect a shoe directly to the pedal, and indirectly to the crank arms, with ease. The cyclist""s foot then disengages the pedal system by rotating or displacing the shoe in a predefined manner or under the force of an accident, for example.
Although the clipless pedal system allows the operator""s foot to quickly connect to and disconnect from the crank, the cleat and corresponding receptacle in prior art systems is located directly below the sole of the cycling shoe. The location of the cleat and receptacle below the cyclist foot detrimentally affect the performance in at least three ways: First, the prior art systems, which can be as much as an inch thick, reduce the ground clearance at the underside of the pedal, thereby reducing limiting the angle at which the bicycle may be simultaneously pedaled and turned. Second, the thickness of the cleat and receptacle system increases the riding height of the cyclist and the frame, thereby increasing aerodynamic drag and bicycle weight. Third, the force exerted by the foot of the cyclist is distributed over the relatively small area of the cleat which increases the pressure of the foot in immediate proximity to the cleat of the foot and causes discomfort to the cyclist.
U.S. Pat. No. 5,586,472 to Lin, U.S. Pat. No. 5,440,950 to Tranvoiz, and U.S. Pat. No. 5,315,896 to Stringer disclose detachable pedal assemblies in which a portion of the release mechanism is located in proximity to the crank arm. In each of these patents, the pedal is mounted either directly or indirectly into the crack through the spindle. The pedal remains rotatably affixed to the crank until a linear force co-parallel to the axis of the spindle is applied. Although these prior art pedal assemblies may be quickly attached to and removed from the crank arm, manual intervention is required without which the pedal cannot be engaged or disengaged. Moreoever, these pedal assemblies are designed to facilitate the assembly and disassembly of the pedal in connection with the storage and transportation of the bicycle. These pedal assemblies do not include means to attach a cycling shoe to the pedal and are, therefore, entirely unsuitable for road racing applications where it is necessary to both press down and lift up the pedal.
The present invention overcomes the limitations of the prior art with a detachable pedal assembly in which the release mechanism is positioned adjacent to the axle that threadedly engages the bicycle pedal crank arm. Location of the release mechanism to the side of the pedal and away from the underside of the cyclist""s foot allows (1) the rider to assume a lower riding position, thereby reducing the frame height and aerodynamic drag; (2) the bottom side of the pedal to be raised, thereby allowing for sharper turns of the bicycle; (3) the pedal to have a greater surface area, thereby reducing the pressure across the cyclist""s foot; and (4) the rider visibility of the release mechanism during engagement, unlike prior art systems.
In one embodiment of the present invention, the detachable pedal assembly is comprised of an axle assembly, binding assembly, and connecting means. The axle assembly is comprised of an axle adapted to threadedly engage the bicycle pedal crank arm. The binding assembly is comprised of a pedal through which the cycling shoe applies force to drive the bicycle. The connecting means is comprised of a bearing and releasable coupling means, the connecting means being substantially interposed between the pedal crank arm and the binding assembly in the lateral direction. Although the bearing and releasable coupling means may be affixed to either the axle assembly or the binding assembly, it is important that the releasable coupling means rigidly hold the binding assembly to the axle assembly until a force equal to or greater than a predetermined force threshold is applied, at which point the release coupling means responds by automatically disengaging the binding assembly from the axle assembly. In this manner, a cyclist may exert force on the pedal assembly without disengaging the pedal crank arm unless the cyclist chooses to disengage the binding assembly from the axle assembly. In some embodiments, the shoe-pedal assembly may be automatically disengaged from the bicycle crank if the cyclist befalls adverse circumstances.
In some embodiments of the present invention are designed with offset between the pedal of the binding assembly and the axle assembly to position the ball of the cyclist""s foot at the axis of the axle. Still other embodiments adapted primarily to bicycle road racing applications include shoe fastening means permitting the cycling shoe to be affixed to the pedal assembly, thereby allowing the cyclist to drive the bicycle by pushing against the pedal in the down stroke as well as pulling on the pedal during the upstroke. The shoe fastening means may be used in combination with a force-responsive locking means that determines the force necessary to release the binding assembly from the axle assembly.
The shoe-pedal assembly in preferred embodiments is made to engage and disengage the axle mounted on the bicycle pedal crank assembly in the vertical direction, while other embodiments permit the binding assembly to engage and disengage the axle in the other directions or manners. The binding assembly may be made to alternatively engage or disengage the axle by means of one or more forces including rotational forces or linear forces applied in the horizontal or vertical plain.